1. Field of the Invention
The present invention relates to a deceleration controlling apparatus for an automotive vehicle, which may perform a deceleration control that is effective when a throttle valve is out of order such as being kept opened, without increasing a cost.
2. Description of the Related Art
FIG. 6 is a view showing a structure of a conventional deceleration controlling apparatus for an automotive vehicle, disclosed in, for example, Japanese Patent Application Laid Open Nos. Hei 5-301535 and Hei 6-264800.
In FIG. 6, an engine 1 mounted on the vehicle is composed of a plurality of cylinders and provided with an intake pipe 2 and an exhaust pipe (not shown).
An air flow sensor (hereinafter referred to as "AFS") 3 is provided on an upstream side of the intake valve 2 for detecting an amount of intake air to be fed to the engine 1 and outputting an intake air amount signal Q.
A throttle valve 4 is provided to be openable/closable within the intake pipe 2, thereby adjusting the intake air amount Q.
A throttle actuator 5 is composed of a motor provided on a rotary shaft of the throttle valve 4 for drivingly opening/closing the throttle valve 4.
A throttle opening degree sensor (TPS) 6 detects an opening degree of the throttle valve 4 to output a throttle opening degree signal T.
A bypass passage 7 is provided in a part of the intake pipe 2 to bypass between the upstream side and the downstream side of the throttle valve 4.
A bypass controlling valve 8 adjusts an opening degree of the bypass passage 7 for controlling an amount of bypass air.
An injector 9 injects a fuel into the interior of the intake pipe 2 on the intake side of the engine 1. Ignition plugs 10 are provided for the respective cylinders of the engine 1 for generating discharge sparks by the application of the ignition high voltage and burning the mixture within the respective cylinders.
An automatic transmission 11 is connected to the engine 1 to automatically adjust a gear speed ratio. A hydraulic solenoid 12 drives the automatic transmission 11 to switch and control the speed ratios.
An accelerator pedal 13 is operated by a driver, and an accelerator opening degree sensor (APS) 14 detects an opening degree of the accelerator pedal 13 to output an accelerator opening degree signal A.
A brake system 15 is composed of a brake pedal 16, a brake switch 17, a booster 18 and a brake working portion 19.
The brake pedal 16 is operated by the driver, and a brake switch 17 detects a step-in amount of the brake pedal 16 to output a brake signal B.
Also, the booster 18 amplifies and transmits the step-in force of the brake pedal 16, and the brake working portion 19 is driven by the output of the booster 18. The booster 18 realizes a booster function by using a vacuum pressure within the intake pipe 2.
A controlling section 20 is composed of a microcomputer for outputting drive signals for the various actuators on the basis of information signals from the various sensors for detecting the operational condition of the engine 1.
Also, the controlling section 20 constitutes a throttle valve controlling means in cooperation with the throttle actuator 5 for electrically controlling the opening degree of the throttle valve 4 in response to the accelerator opening signal A.
The drive signals outputted from the controlling sections 20 are a motor drive signal M for the throttle actuator 5, a bypass drive signal D for the bypass controlling valve 8, an injection signal J for the injector 9, an ignition signal P for the spark plug 10, a speed-change signal C for the hydraulic solenoid 12 and the like.
Also, a variety of sensors for detecting the operational condition are an RPM sensor 21, a load sensor 22, a vehicle velocity sensor 23 and the like as well as the AFS 3, the TPS 6 and the APS 14.
The RPM sensor 21 is provided on, for example, a crankshaft of the engine 1 for detecting the engine RPM and outputting an RPM signal Ne.
The load sensor 22 detects the load of the engine 1 and outputs a load signal L. The vehicle velocity sensor 23 detects a velocity of the vehicle to output a vehicle velocity signal V.
Also, an apparatus in which a hydraulic pressure (brake force) working on the brake working portion 19 is controllable as desired to thereby further enhance the drivability in deceleration has heretofore been proposed.
FIG. 7 is a view showing a structure of a conventional vehicle deceleration controlling apparatus that may control the brake force.
In FIG. 7, the same reference numerals are used to indicate the like components or members as in FIG. 6, and therefor the detailed description thereof is omitted.
In this case, the brake system 15 is provided with a pump 24 and a reservoir 25 which constitute a hydraulic pressure adjusting means for adjusting the hydraulic pressure to thereby drive the brake working portion 19.
The pump 24 is in communication with the booster 18 and the brake working portion 19 for feeding and collecting oil for the reservoir 25.
Also, the controlling section 20A includes a hydraulic controlling means for controlling the pump 24 of the hydraulic pressure adjusting means to output a pump drive signal R for the pump 24.
As shown in FIGS. 6 and 7, the conventional vehicle deceleration controlling apparatus utilizes the vacuum pressure within the intake pipe 2 of the engine 1 for the booster 18 within the brake system 15.
Also, in consideration of the case where the vacuum pressure within the intake pipe 2 is insufficient, a vacuum pump (not shown) or the like is provided as desired.
Also, in the conventional apparatus disclosed in the above-described Japanese Patent Application Laid-Open No. Hei 5-301535, in the case where the throttle valve 4 is broken down while being kept fully closed, the speed ratio pattern of the automatic transmission 11 is changed on the low gear ratio side.
Also, in the conventional apparatus disclosed in the above-described Japanese Patent Application Laid-Open No. Hei 6-264800, in the case where the throttle valve 4 is broken down while being kept opened, the speed ratio pattern of the automatic transmission 11 is fixed to a third speed.
However, in the above-described conventional apparatus, in the case where the throttle valve 4 could not be closed below a certain opening degree due to a breakdown such as being kept open, the cylinder stop control (interrupt of the fuel injection) of the engine 1 or a retard control of the ignition timing is effected to suppress the generated torque of the engine 1 to mainly prevent an abrupt start or an abrupt acceleration.
In such conventional apparatus, in the case where the throttle valve 4 is broken down while being kept opened, no vacuum pressure is generated in the intake system of the engine 1 so that it is impossible to provide the vacuum pressure to the booster 18 within the brake system 15.
As a result, since the function of the booster 18 is degraded, the step-in force that is necessary when the brake-pedal 16 is stepped in is increased, resulting in degradation of the work of the brake system 15.
Also, in the case where the throttle valve 4 is broken down while being kept opened, the automatic transmission 11 is fixed to a predetermined higher speed-change stage, i.e., a predetermined lower gear speed-change ratio (for example, corresponding to a third speed) to thereby suppress the drive force to prevent an abrupt start or an abrupt acceleration.
Accordingly, in deceleration, due to the degradation of the work of the brake system 15, it is impossible to obtain a sufficient brake force. It is therefore difficult to decelerate the vehicle.
Also, in the breakdown in the open throttle condition, the gear ratio is fixed to a lower gear reduction ratio (a higher speed) so that a relatively high vehicle velocity would be attained even in a low engine RPM. For this reason, in braking the vehicle, an idle running feeling occurs, and it is difficult to stop the vehicle.
As described above, the conventional vehicle deceleration controlling apparatus suffers from a problem that, since the brake system 15 is functioned by using the vacuum pressure in the intake system, in the case where the throttle valve 4 is broken down while being kept opened, the vacuum pressure in the intake system is insufficient so that the booster 18 functions at a low level, resulting in degradation of the work of the brake system 15.
Also, in the case where the throttle valve 4 is broken down while being kept opened, since the automatic transmission 11 is fixed to a predetermined relatively high speed (for example, corresponding to a third speed), that is, a predetermined lower gear reduction ratio, to thereby suppress the drive torque, the function of the brake system 15 becomes worse in deceleration, resulting in the difficulty to obtain a sufficient brake force. Thus, the conventional apparatus suffers from a problem that it is difficult in obtaining decelerate the vehicle.
Furthermore, in the case where the throttle valve 4 is broken down while being kept opened, since the gear reduction ratio is fixed to a lower level (i.e., a relatively high speed corresponding to a third speed), a relatively high vehicle velocity is attained even at a low engine RPM of the engine 1. Accordingly, in braking the vehicle, an idle running feeling occurs, and it is difficult to stop the vehicle.